Our team is looking to add weight to redistribute our center of gravity in a cheap and legal fashion. Any recommendations? Please assume that the motors and battery and NXT are fixed, we are looking to ADD not move around. Thank you!
The most dense legal material (other than the battery and maybe the motors, which are already positioned) is probably the steel of the Tetrix axles and the Tetrix screws. Neither is very cheap as ballast, but based on rough volume caclulations, it seems the 1.5" Tetrix screws, with their heads cut off, would pack closesly and be similarly dense to a bunch of Tetrix axles, but at a lower price per unit volume.
If you want to use axles, the 250mm Tetrix axles are cheaper than the 100mm ones, by volume.
Of course other non-Tetrix screws would be cheaper, but you can’t use them unless they are the same thread type, and even then they cannot be used except as fasteners, IIRC.
Maybe you could find some identical in every way to the Tetrix ones, but for a lower price, and maybe that would pass the rules.
I suppose you could check the price and density of the allowed (steel) wire rope also, but it probably isn’t a great candidate for ballast.
On 1902 we use Gear “totem poles” since we have almost 50 gears laying around from over the years. Even with a 26 gear drive train alone and super structure we used gears to bring the CG lower/add weight to the bot.
If you have any laying around their weight compounds quickly.
Given that TETRIX-compatible fasteners are allowed (double check the rules for specific wording), the bolts used for ballast may actually be fairly cheap if purchased in bulk (such as boxes of 100).
TETRIX-compatible fasteners are allowed–but for use as “fasteners” only. (Maybe you can “fasten” two plates together with about 500 bolts. :eek: )
I have heard that some students’ heads are among the densest objects in the universe.
Do you have any team members who don’t use theirs more than once or twice a day (perhaps just at feeding time)?
Maybe you could borrow one for a while on the day of the competition?
I suppose depleted uranium is right out then.
For our bot we had used the big gears to counter balance our weight and the battery up front.